The prior art includes a variety of techniques and algorithms for improving the quality of digitally recorded and transmitted audio data. These techniques include altering audio pitch.
One prior art technique achieves pitch shifting by seamless time-scale modification (TSM) and restoration of the original time scale through sampling rate conversion. Pitch shifters embedded in karaoke systems use this principle permitting adjustment of the key of a song accompaniment to the singer's voice. Previous approaches to pitch conversion generally employ either: constant pitch shift of the entire signal as seen in common key-shifting algorithms; or complex algorithms that rely on manually labeled databases, speech production models and/or frequency domain processing.